The invention relates to a method and a device for determining a contour, at least in regions, of at least one additively manufactured component layer.
Additive manufacturing methods relate to processes in which material is deposited layer by layer on the basis of digital 3D construction data in order to construct a component of an aircraft engine, for example, in an additive manner. Accordingly, additive or generative manufacturing methods differ from conventional material-removal or primary forming methods of fabrication. Instead of milling a workpiece from a solid block, for example, additive manufacturing methods construct components layer by layer from one or more materials. Examples of additive manufacturing methods are additive laser sintering or laser melting methods, which are used to produce components for aircraft engines, for example. Such a method is already known from DE 10 2004 017 769 B4, for example. In selective laser melting, thin powder layers of the material or materials used are applied onto a construction platform and locally melted and solidified by one or more laser beams. Afterwards, the construction platform is lowered and another layer of powder is applied and again locally solidified. This cycle is repeated until the finished component is obtained. The finished component can subsequently be further processed as needed or can be used immediately. In selective laser sintering, the component is produced in a similar way by laser-assisted sintering of powder-form materials.
In the additive manufacture of components, process fluctuations can lead to construction defects or flaws, which have a detrimental effect on the quality of the component. In this process, the structure or roughness of the component surface of an additively manufactured component is crucial for the solidity and hence for the quality of the component. Although outer component surfaces can still be post-processed—for example, smoothed or polished—with a certain effort, this is no longer possible for the inner surfaces, such as, for instance, for 3D cooling ducts of engine components. The manufacture of complex inner 3D structures and undercuts, however, especially represents one of the main advantages of generative or additive manufacturing methods. Therefore, it would be necessary already during the additive manufacture of the component, to detect the edge region(s) thereof in order to be able to carry out an evaluation of the surface condition. In particular, it would be desirable to be able to detect the inner surfaces in the case of hollow and complexly formed components.
For the currently known devices and methods, however, a determination and evaluation of the contour lines of individual component layers is not possible or only possible in a very limited manner, because, during the additive manufacture of the component layer, particularly the edges are overexposed owing to the melt glow of the adjacent surface structures. As a result, as a matter of principle, image recordings of the component layer cannot be evaluated because of the overexposure of the contour lines. After the manufacture of the individual component layers, however, an evaluation of the edge region is also not possible or only possible in a very limited manner, because the powder layer directly adjacent to the solidified component layer strongly impedes or even renders impossible a correct detection and evaluation of the edge region.